(a) When important changes affecting navigation are to take place in the near future, a Notice to Mariners describing the change will be published so that the mariners will have advanced information on the change. Such notices will be designated (P).
(b) When a change in conditions affecting navigation has taken place but full information is not available, a (P) notice giving available information will be published. This notice will be followed by a regular notice when complete information becomes available. The regular notice will cancel the (P) notice.
(c) When changes have taken place which is too complex to describe in a written notice, a (P) notice giving general information will be published. This notice will explain that follow up action will be taken to update charts by publishing patch corrections, new editions or new charts.